Commonly, beacon lights are made using a Fresnel lens revolved around a central light source. In the past, incandescent bulbs or other traditional light sources were used. More recently LEDs have been used as the light source.
This approach using a Fresnel lens suffers from several deficiencies. One deficiency arises because the outer surface of the Fresnel lens has optical features and is not smooth. Dirt and ice may accumulate and obstruct the light output. A second deficiency is the poor optical efficiency of the Fresnel lens when used with common high-power LEDs.
In addition, the high power LEDs are being used in more applications. However, high power LEDs generally emit light in a very wide angular pattern. This wide pattern does not work well with the revolved Fresnel lens because most of the high-angle light is not collected by the Fresnel lens.